Power vs HR Zone Discrepancy

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    I have a persistent issue where I perform bike workouts in the exact power zones recommended (because I load the workout in zwift), but my heart rate is usually in a zone or two higher. When there’s a mismatch between power and heart zones, which is better to focus on? For instance, I did CCI20 today, and in the 43 minute zone 2 portion, my heart rate was at the top half of zone x the whole time.

    My zones are tested every couple months through cp20 tests in zwift. Should I continue workouts like this in the recommended power zones, or reduce the power to get my heart rate in the right zone? I didn’t experience any cardiac drift during the steady portion.


    David Warden


    This is such an interesting trend to me. I probably went 4 years without an athlete saying their HR zones were higher than power zones (plenty of questions about HR being lower than power zones which is the more common issue). Then I’ve had 3 questions in a row recently where HR is higher than power zones. It’s time to write a full article!

    Here’s what I’ll say in that article:

    – First, unless the athlete performs the full 30-minute threshold test and captures both HR and Power at the same time, it is very unlikely that the two will align. The two intensities must be measured at the same time, in the same test, for the full 30.

    – Second, even if you do measure both at the same time with the full 30-minute test, unless you train the exact same environment as your test, the two will continue to not be aligned. Remember, HR is significantly influenced by external factors. A 250 watt FTP in a 70 degree environment will be an LTHR of 165. The same 250 watts will be 180 bpm at 85 degrees.

    – Finally, to answer your direct question, use Power. Not HR. Power is more reliable and consistent.

    What’s interesting is that your HR is higher than Power while indoors. That is unusual. Indoors usually depressed HR to be 5-10 beats lower than outside.

    I recommend you perform your next test for 30 minutes and I suspect your LTHR is going to be 5+ beats higher than you thought. Report back here!



    Either my LTHR will be 5+ beats higher, or my FTP will be 10+ watts lower 😂. All my training and testing is indoor, so things are very consistent with me. I’ve got a CT31 scheduled for January 7. I’ll substitute a CP30 there and report back.



    I retested using the 30 minute test as was recommended, and my heart rate zones match much more closely with the power zones.



    Awesome, going to have to do a new FTP test.

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